Re: How to create a plugin to instrument function calls?

[Paul <pgsery at swcp dot com>]

Ian Lance Taylor<iant@google.com>  said:

>  "Paul Sery"<pgsery@swcp.com>  writes:
>
>  >  I want to create a plugin that inserts custom code before function calls. The
>  >  plugin would mimic the way fprofile-arcs instruments function calls, but not
>  >  other structures. For instance, I'd like to modify the following code,
>  >  ...
>  >  I think/guess the best place for this to occur is in the assembler, like
>  >  finstrument-functions?
>
>  The assembler is an OK place to hack things which change the function
>  prologue or epilogue.  It sounds like you want to change the actual body
>  of the function, which is quite different.  I would suggest working at
>  the GIMPLE level instead, and modifying function calls there.

Ok, I'll go that route. Do you think it better recycle an existing function like the one
finstrument-functions option uses?
  ...
  profile_function_entry_libfunc
    = init_one_libfunc ("__cyg_profile_func_enter");
  --->
  profile_function_entry_libfunc
    = init_one_libfunc ("__myfn");

or perhaps mimic the way the gcov option works?
   ...
   = build_function_type_list (void_type_node,...
   = build_fn_decl ("__gcov_interval_profiler",
   ...

Thanks,
Paul